Apparatus and methods for mitigating electromagnetic emissions

• US 8,415,839 B2
• Filed: 01/09/2009
• Issued: 04/09/2013
• Est. Priority Date: 01/09/2009
• Status: Active Grant

• Current Assignee: Nasa Headquarters
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Geng, Steven M., Niedra, Janis M.
• Primary Examiner(s): Nguyen, Tran
• Assistant Examiner(s): PHAM, LEDA T
• Application Number:
  US12/319,617
• Publication Number:
  US 20110175369A1
• Time in Patent Office: 1,551 Days
• Field of Search: 310 1201- 1233, 310 15- 36, 417/416, 417/417, 417/44.1, 417/44.11
• US Class Current: 310/15
• CPC Class Codes: H02K 11/014 Shields associated with stationary parts, e.g. stator cores
• CPC Class Codes: H02K 11/0141 Shields associated with casings, enclosures or brackets
• CPC Class Codes: H02K 33/16 with polarised armatures moving in alternate directions by reversal or energisation of a single coil system
• CPC Class Codes: H02K 35/02 with moving magnets and stationary coil systems
• CPC Class Codes: H02K 7/1876 with reciprocating, linearly oscillating or vibrating parts

Abstract

Apparatus, methods, and other embodiments associated with mitigation of magnetic fields are described herein. In an embodiment, a method for mitigating an electromagnetic field includes positioning a mitigating coil around a linear alternator of linear motor so that the mitigating coil is coaxially located with an alternator coil; arranging the mitigating coil to generate a field to mitigate an electromagnetic field generated by the alternator coil; and passing an induced current from the alternator coil through the mitigating coil.

Claims

1. A electromagnetic field mitigation system comprising:

a linear alternator or linear motor comprising;

a magnet linearly movable along a path; and

an alternator coil positioned about the magnet and configured to generate an electromotive force, resulting in a first magnetic field;

a mechanism coupled to the linear alternator or linear motor to linearly oscillate the magnet along the path; and

a mitigating coil positioned about the linear alternator or linear motor and configured to generate a second magnetic field, wherein the second magnetic field is configured to cancel out an externally emitted portion of the first magnetic field.

2. The electromagnetic field mitigation system of claim 1, where the mitigation coil is connected in series with the alternator coil.

3. The electromagnetic field mitigation system of claim 1, where the mechanism is a Stirling engine.

4. The electromagnetic field mitigation system of claim 3, where the Stirling engine is an Advanced Stirling Radioisotope Generator.

5. The electromagnetic field mitigation system of claim 1, where an electrical current passing through the mitigation coil travels in a direction opposite of an electrical current passing through the alternator coil.

6. The electromagnetic field mitigation system of claim 1, where the linear alternator or linear motor includes a stator positioned between the mitigation coil and the alternator coil.

7. The electromagnetic field mitigation system of claim 6, where the mitigation coil is adjacent to an outer surface of the stator.

8. The electromagnetic field mitigation system of claim 1, where the mitigation coil is positioned to be coaxial with the alternator coil.